fMRI Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Galeazzi, 20161 Milan, Italy;
Psychology Department, University of Milan-Bicocca, 20126 Milan, Italy.
Proc Natl Acad Sci U S A. 2018 Jul 10;115(28):7440-7445. doi: 10.1073/pnas.1718891115. Epub 2018 Jun 27.
Here we challenge and present evidence that expands the , , and anatomical model of intentional action, which states that internally driven decisions about the content and timing of our actions and about whether to act at all depend on separable neural systems, anatomically segregated along the medial wall of the frontal lobe. In our fMRI event-related paradigm, subjects acted following conditional cues or following their intentions. The content of the actions, their timing, or their very occurrence were the variables investigated, together with the modulating factor of intentionality. Besides a shared activation of the pre-supplementary motor area (pre-SMA) and anterior cingulate cortex (ACC) for all components and the SMA proper for the when component, we found specific activations beyond the mesial prefrontal wall involving the parietal cortex for the component or subcortical gray structures for the component. Moreover, we found behavioral, functional, anatomical, and brain connectivity evidence that the self-driven decisions on whether to act require a higher interhemispheric cooperation: This was indexed by a specific activation of the corpus callosum whereby the less the callosal activation, the greater was the decision cost at the time of the action in the whether trials. Furthermore, tractography confirmed that the fibers passing through the callosal focus of activation connect the two sides of the frontal lobes involved in intentional trials. This is evidence of non-unitary neural foundations for the processes involved in intentional actions with the pre-SMA/ACC operating as an intentional hub. These findings may guide the exploration of specific instances of disturbed intentionality.
在这里，我们提出并提供证据，挑战了传统的关于意向性行动的解剖学模型，该模型认为内部驱动的关于我们行动的内容和时间以及是否采取行动的决策取决于可分离的神经系统，这些系统沿着额叶的内侧面解剖上分离。在我们的 fMRI 事件相关范式中，受试者根据条件线索或根据他们的意图采取行动。我们一起研究了行动的内容、时间或其发生，以及意向性的调节因素。除了所有组件的预备运动区（pre-SMA）和前扣带皮层（ACC）的共同激活以及 SMA 本身对于“何时”组件的激活之外，我们还发现了超出内侧前额叶壁的特定激活，涉及顶叶皮层对于“什么”组件，或者涉及皮质下灰色结构对于“是否”组件。此外，我们发现了行为、功能、解剖和脑连接的证据，表明自我驱动的关于是否采取行动的决策需要更高的大脑半球间合作：这是通过胼胝体的特定激活来索引的，其中胼胝体的激活越少，在“是否”试验中行动时的决策成本就越大。此外，轨迹分析证实，穿过胼胝体激活焦点的纤维连接了参与意向性试验的两个额叶侧。这是涉及意向性行动的过程的非单一神经基础的证据，pre-SMA/ACC 作为意向性中枢运作。这些发现可能指导对特定的意向性障碍的探索。
